When I'm home alone, I at times hear a crackling sound. Most of the time like a plastic water bottle crinkling up. Other times, it sounds like water draining in a sink. I would hear it in my room or outside my window or even in the hall. Mostly in my room though.

All houses make these noises. A house is constantly "settling", creaking, cracking.Some very old houses do it more than others.Then they get a reputation as being "haunted". Don't worry about it.Those "noises" are natural!

You learn from physics that energy cannot cease- kinetic (movement) energy can transfer into other types of energy and be passed on etc.

It's like when you watch a TV and have the sound on fairly loud, when you turn it off, the tv sometimes makes a cracking noise, it is just the energy from sound- that is sound energy, heat energy and kinetic energy transferring through the plastic of the TV and being transferred into the air or surrounding area.

Your house does the same, with central heating, footsteps, temperature changes which occur at night etc.